Not sure that is one of their official domains? https://solidtorrents.eu and https://solidtorrents.to seem to be up at the moment - but you’re right their uptime has been spotty.

As an alternative you could always check if https://bitsearch.to is up, that site is run by the same admin and shares the same torrent database AFAIK.

I don’t know if the site admin is around on Lemmy, they are (or used to be) on Reddit.